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    Recovering bioactive compounds and antioxidant capacity of medium roasted spent coffee grounds through varied hydrothermal brewing cycles
    (2025-04-01)
    Maiyah, Nur
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    ; ;
    Kerr, William L.
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    Spent coffee grounds (SCGs) are the residual product from brewing coffee and contain valuable bioactive compounds. This study investigated the effects of hydrothermal brewing cycles on the bioactive compounds and antioxidant capacity of medium roasted Arabica (A) and Robusta (R) SCGs. SCGs from A and R were prepared using 3 levels of brewing cycles at 92–95 °C/900 kPa. The SCGs were collected and air dried at 60 °C to achieve a moisture content of less than 4 % wb. Field emission scanning electron microscopy (FE-SEM) imaging showed that brewing increased SCGs porosity, allowing more moisture retention and enhanced extraction of compounds on subsequent cycles. SCGs also became less pigmented after additional brewing. Fourier-transform infrared (FTIR) spectra confirmed the retention of chemical components after each cycle, indicating a level of stability in the functional groups. Ethanol extraction yielded higher total phenolic content (TPC), while water extraction resulted in greater total flavonoid content (TFC); however, both decreased with additional hydrothermal brewing cycles. Caffeine and chlorogenic acid were more abundant in ethanol extracts, whereas water extracts exhibited stronger antioxidant activity (measured by ABTS and FRAP), particularly in Robusta SCGs. The bioactive compounds and antioxidant capacity were reduced with additional SCGs brewing. Significant correlations between TPC, TFC, caffeine, and antioxidant measures underscore the potential for the sustainable reuse of SCGs as a bioactive resource. Overall, hydrothermal brewing cycles enhanced the extraction and utilization of bioactive compounds from SCGs, contributing to the development of value-added products that promote health and sustainability.
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    Process optimization, antioxidant activity and sensory characteristics of green tea made from young fragrant rice leaves cultivar Damgatondam
    (2019-01-01)
    Uthai, N.
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    Thamakorn, P.
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    ;
    Nokkoul, R.
    Green tea was made from one-month old leaves of the Thai upland black waxy rice cultivar Damgatondam (DGTD), which has a pleasant smell of jasmine. The objective was to determine the optimum process required to produce green tea that is acceptableto consumers and has health benefits. The processing conditions were steaming at 98 ± 2°C for 30, 45, 60 75, 90 or 105 sec then pan roasting at 70 ± 2°C for 5, 10, 15, 20, 25 or 30 min and finally tray drying by using electrical cabinet tray dryer at 60 ± 2°C for 30, 45, 60 or 90 min. Brewed samples were compared to brewed samples of seven commercially available Camellia sinensis tea products by descriptive analysis with 10 trained panelists. The highest quality of DGTD tea was: steaming at 98 ± 2°C for 60 sec, which completely inactivated peroxidase enzymes and preserved the green color, followed by pan roasting at 70 ± 2°C for 30 min and tray drying at 60 ± 2°C for 90 min in order to achieve a moisture content of less than 5%. The proximate analysis showed the DGTD tea prepared by the above method had: 3.77% moisture content, 7.94% ash, 22.59% crude fiber, 2.58% fat and 17.73% protein. Moreover, Ca, Mg, K, Fe, Mn and Na were 3400, 3200, 20400, 66.4, 139.1 and 113.8 mg/kg, respectively. It was found that protein, fat, crude fiber, ash, Mg, K and Na contents in DGTD tea, were higher than levels in tea from Camellia sinensis. Total phenolic content of DGTD tea was 9.53 mg GAE/g and antioxidant activity was 357.52 mM TE/g by Ferric reducing antioxidant power ( FRAP) , l34.08 mM TE/g by 2,2 diphenyl-1-picrylhydrazyl assay (DPPH) and 108.89 mM TE/g by 2,2'-azino-bis ( 3-ethylbenzothiazo line-6-sulphonic acid) ( ABTS) . The descriptive analysis of trained panels identified 11 particular attributes of DGTD tea, consisting of yellowness, clearness, tea odor, hay odor, green odor, seaweed odor, jasmine rice odor, tea flavor, seaweed flavor, bitter taste and astringent taste. The descriptive analysis showed that the DGTD tea was less bitter and astringent than the Camellia sinensis tea and its jasmine odor was positively accepted.
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    Luffa sponge offsets the negative effects of aeration on bacterial cellulose production
    (2016-12-01)
    Krusong, W.
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    ; ;
    Aims: To offset the negative effects of aeration on bacterial cellulose (BC) production by acetic acid bacteria using enmeshed cellulose microfibrils (CM) on luffa sponge matrices (LSM). Methods and Results: The CM were enmeshed on LSM (LSM-CM). The optimal amount of LSM-CM was determined for BC production under aerated conditions. Without LSM-CM, no BC was produced in seven out of nine production cycles at the highest aeration rate (9 l min<sup>−1</sup>). However, with 0·5% LSM-CM and an aeration rate of 3 l min<sup>−1</sup>, a satisfactory oxygen transfer coefficient was achieved, and also a good yield of BC (5·24 g l<sup>−1</sup>). Moreover, the LSM-CM was able to be recycled through nine consecutive BC production cycles. The highest BC yields (from 5·8 ± 0·4 to 6·6 ± 0·4 g l<sup>−1</sup>) were associated with high bacterial biomass and this was confirmed by scanning electron microscopy. Conclusions: We confirm that LSM-CM works well as a starter. Microenvironments low in dissolved oxygen within the matrices of LSM-CM are important for BC production under aeration conditions. Significance and Impact of the Study: The LSM-CM provides a microenvironment which offsets the negative effects of aeration on BC production. A sustainable, economic process for mass BC production is described using recycled LSM-CM with aeration.
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    Influence of calcium chloride in the high temperature acetification by strain Acetobacter aceti WK for vinegar
    (2015-11-01)
    Krusong, W.
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    ; ;
    Yaiyen, S.
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    Pornpukdeewatana, S.
    Aims: To improve the thermotolerant properties (TTP) of acetic acid bacteria (AAB) cells for high temperature acetification. Methods and Results: At high temperature (36 ± 1°C), the acetification rate (ETA) is usually lower than at 30 ± 1°C. The addition of 0·15% calcium chloride (CaCl<inf>2</inf>) may decrease the negative effect of the increase of temperature from 30 ± 1°C to 36 ± 1°C on the ETA. The effect of CaCl<inf>2</inf> on the thermotolerant properties of acetic acid bacteria cells was investigated. The CaCl<inf>2</inf> increased the content of phospholipids (phosphotidylcholine and phosphatidylglycerol), fatty acids (cis-vaccenic acid, palmitic acid and myristic acid) and the activities of membrane-bound enzymes involved in acetification, alcohol dehydrogenase and aldehyde dehydrogenase. Transmission electron microscope images revealed a more compact cell wall with CaCl<inf>2</inf>. Process consistency at 36 ± 1°C was tested in nine sequential acetification cycles using 0·15% (w/v) CaCl<inf>2</inf>. High ETAs (9·33 ± 0·6; 8·67 ± 0·8 and 9·67 ± 0·7 g l<sup>-1</sup> day<sup>-1</sup>) were obtained during the last three cycles. Conclusions: The results confirm that changes of the content of lipid, activities of membrane-bound enzymes and cell-wall thickness occurred with added CaCl<inf>2</inf>. Significance and Impact of the Study: High temperature acetification (HTA) with additions of CaCl<inf>2</inf> was investigated. Significant reductions in the overall production costs result from lower cooling costs associated with HTA.
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    Upland rice vinegar vapor inhibits spore germination, hyphal growth and aflatoxin formation in Aspergillus flavus on maize grains
    The efficacy of vapor-phase (VP) upland rice vinegar (URV) was investigated as a bio-fumigant for maize, to reduce consumer health risks associated with spore and toxin formation by Aspergillus flavus. Complete reduction of mycelial growth occurred with in vitro VP exposure to URV (containing 0.0017 mmol/L acetic acid) or with VP exposure to pure acetic acid (PAA) (containing 0.0023 mmol/L acetic acid). No significant differences were observed between the two materials after 90 min exposures. Using gas chromatography-mass spectrometry (GC-MS), URV vapor was shown to contain volatiles having antifungal activities. These are identified as isoamylalcohol, 1-butanol, 3-methyl-, acetate and β-phenylethyl acetate. It is suggested these volatiles increase the antifungal effectiveness of URV. Exposure to VP-URV (containing 0.0043 mmol/L AA) for 5 h completely eliminated viable spores of A. flavus on maize seeds (23% moisture content) previously inoculated with 4.43 ± 0.28 log spores/g). At the same time, aflatoxin production decreased, as VP-URV exposure increased. Hence, VP-URV is shown to be an effective control agent for A. flavus mycelial growth and aflatoxin formation on maize, so effectively reducing the potential for consumer health risks due to this widespread fungus.
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    Sous-vide meat properties as a function of physical and surface changes during processing
    (2022-01-01) ;
    Kerr, William L.
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    Klaypradit, Wanwimol
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    Sous-vide is a method of cooking of vacuum-packed samples at relatively low temperature for longer periods than practiced with conventional cooking. Sous-vide is applicable to a wide variety of foods, and optimized sous-vide processing of meat can result in more tender products with less cooking loss. In this study, chicken breast and Thai local beef round were compared under sous-vide (vacuum-packaged and cooked at 60 to 80 °C for 1 to 7.5 h) and traditional cooking temperatures. The physical properties and surface texture of meat during sous-vide cooking were determined. It was found that the L<sup>*</sup> (lightness) and a<sup>*</sup> (redness) of cooked chicken breast were not affected by cooking temperatures or times (p >0.05), while the color of cooked beef depended on both temperature and time (p ≤0.05). It was found that cooking at higher temperature and for longer time resulted in meat with lower cooking yield and higher sous-vide loss, but with less re-heating loss (p ≤0.05). These results were supplemented with surface texture images which showed that larger spaces developed between the fibers after cooking at higher temperatures for longer time than those for samples cooked by sous-vide. Sous-vide chicken breast cooked at 60 °C for 2 h and 80 °C for 0.5 h, as well as beef cooked at 60 °C for 2.5 h and 80 °C for 2 h, were the most tender as measured by the lowest shear force values.
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    Structural changes in local Thai beef during sous-vide cooking
    (2021-05-01)
    Supaphon, Pattama
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    Vénien, Annie
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    Loison, Olivier
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    Sicard, Jason
    Thai beef (Bos indicus) samples were sous-vide-cooked at temperatures of 60°C, 70°C or 80°C for 2 to 36 hrs and prepared for microstructure characterization by light and electron microscopy. Muscle fibers showed a first phase of lateral shrinkage during the first 6 hrs of cooking at 60–70°C and the first 2 hrs at 80°C followed by a second phase of significant alternations of shrinkage and swelling independently of water transfers. Swelling peaked at 12 hrs. Microstructural changes were more variable for samples cooked at 60–70°C than for samples cooked at 80°C that showed a larger cross-sectional myofibrillar mass area (CSA). Hypercontracted fibers were evidenced at all temperature–time combinations and were associated with adjacent wavy fibers and a characteristic structural evolution in the mitochondria. The role of thermal denaturation of proteins and the ultrastructural analogy of hypercontracted fibers with cold-shortened fibers are discussed.
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    Drying effects on physicochemical and functional properties of cuttlefish (Sepia officinalis) ink powder
    (2024-09-01)
    Salsabila, Salma
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    Kerr, William L.
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    This study investigated the physicochemical, functional, and organoleptic properties of cuttlefish (Sepia officinalis) ink powder prepared by freeze drying and hot air tray drying. Key proximate and physicochemical properties were measured to assess differences due to drying method. In addition, organoleptic tests were conducted on cuttlefish ink powder incorporated into spaghetti sauce. Freeze-dried powders had slightly higher moisture (9.86 %) than tray-dried powders (7.65 %) and more ash (15.04 versus 13.19 %). Both samples had ∼43 % protein, a light-brown to black color and a pH of 5.5–5.6 when rehydrated. There were no differences in loose or tapped density and Hausner ratios of 1.30–1.35 suggest the powders had ‘passable’ flow. Overall protein solubility varied with pH and freeze-dried materials generally had greater solubility. FT-IR showed no differences in peaks derived from organic components. FE-SEM showed both samples had spherical granules that formed 100–200 nm clusters; however, the surface texture of tray-dried powders was rougher than the freeze-dried samples. Consumer tests showed higher overall likability for spaghetti sauce with fresh ink compared to dried ink powders. Differences were attributed more to texture than to flavor or appearance. Cuttlefish ink can be utilized in the food industry, particularly as a natural flavor, food coloring or additive.
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    Synthesis of soluble calcium compound from skipjack tuna bones using edible weak acids
    (2022-06-01)
    Aenglong, Chakkapat
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    Wang, Yu Ming
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    Limpawattana, Maruj
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    Sukketsiri, Wanida
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    Tang, Qing Juan
    This study aimed to enhance the water solubility of calcium from tuna (Katsuwonus pelamis) bones (TB). Calcium hydroxyapatite (HA) was obtained by calcination of TB. For mineral profiles of TB and HA, Ca had the highest content followed by P with Ca/P of 3.47 and 1.94. Mg, K, and Na as macro minerals and Cr, Cu, Mn, and Zn as micro minerals were also found. Subsequently, HCl was applied to form structured HA-chloride compound (HA-Cl) then reacted with alkaline to obtain structured HA-hydroxide compound (HA-OH). In order to enhance the water solubility, citric and lactic acid were individually reacted with HA-Cl and HA-OH to obtain structured HA-citrate compounds (HA-Cl-Ci and HA-OH-Ci) and structured HA-lactate compounds (HA-Cl-Lac and HA-OH-Lac). HA-Cl-Ci had the highest water solubility (93.34 ± 0.45%) followed by HA-OH-Lac (90.35 ± 0.23%) with Ca/P ratio of 2.28 and 2.24, respectively. HA-Cl-Ci and HA-OH-Lac demonstrated the similar mineral profiles to those of HA but with different contents. The results of FT-IR indicated the carboxyl group of acid played an important role in binding Ca<sup>2+</sup>. X-ray diffractograms indicated that calcined bone was HA whereas the major composition of HA-Cl-Ci and HA-OH-Lac was related to calcium citrate tetrahydrate and calcium lactate pentahydrate, respectively.
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    Impact of roasting levels and brewing cycles on bioactive compounds in spent coffee grounds
    (2026-02-01)
    Maiyah, Nur
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    ;
    Kerr, William L.
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    Klaypradit, Wanwimol
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    Smithisukul, Chayada
    Spent coffee grounds (SCGs) represent a potential source of residual bioactive compounds for sustainable reuse. Effects of roasting levels and sequential brewing cycles on recovery of total phenolic content (TPC), total flavonoid content (TFC), caffeine, and chlorogenic acid (CGA) from Arabica and Robusta SCGs were investigated. Coffee beans were roasted (light, medium, dark), brewed through three hydrothermal cycles, and the resulting SCGs extracted with 70% ethanol. The first brewing cycle removed most water-soluble bioactive compounds, while subsequent brews induced smaller compositional changes, indicating the persistence of functional compounds. Roasting influenced the initial bioactive profile, but its impact diminished after brewing. Robusta SCGs retained higher TPC and antioxidant activity while caffeine diminished with brewing cycle, they were relatively stable to roasting while CGA was more heat-sensitive. Principal component analysis confirmed brewing history as the main factor governing SCG chemical profiles. These findings support brewing-informed SCG valorization for sustainable functional food applications.